# What is the formula for Hydroarsenic acid?

Perhaps ${H}_{3} A s {O}_{4}$...........
The is the arsenical analogue of phosphoric acid, ${H}_{3} P {O}_{4}$. $\text{Arsenate}$, and $\text{phosphate}$ salts behave very similarly; i.e. in general their salts are as soluble as bricks.